Table 5. Characteristics of the eccentric training.
Study Eccentric Training Protocol Load Frequency Volume Progression Strategy Pain Monitoring Comparator Group Comparator Details Adverse Events/Harms
Pattelar tendon
(Abat et al., 2016) Incline eccentric squats (25° decline), single-leg Bodyweight only 3×/week 3×15 reps Fixed (no structured progression; until VISA-P ≥ 90) VISA-P Yes Group 1: Electro-physiotherapy (US, Laser CO2, IFC, 3×/week × 8w); Group 2: USGET (every 2w, 3 punctures, US-guided) None reported
(Bahr et al., 2006) Decline-board eccentric squats (25°), single-leg eccentric Bodyweight → backpack (5-kg increments) 2×/day 3×15 reps per session Load adjusted to maintain pain 4–5/10 VISA, VAS Yes Group 2: Open surgical debridement + postop rehab; Secondary surgery if training failed None reported
(Biernat et al., 2014) Decline-board squats (25°), added unstable surface + functional training Bodyweight Daily (except match/training days) 3×15 reps (per leg) Progression by unstable surface/ functional additions VAS (stop if >4/10) Yes Control: Volleyball training only None reported
(Breda et al., 2021) Pain-provoking EET, single-leg decline squat (25° board) Bodyweight → backpack weights 2×/day 3×15 reps Increase load with backpack if pain ≤3/10 Pain ≥5/10 during exercise; ≤3/10 to progress Yes PTLE (progressive tendon- loading: isometric → isotonic → plyometric → sport-specific) None reported
(Cannell et al., 2001) Drop squats, rapid knee unlocking Bodyweight → hand weights (2–18 kg) 5×/week 3×20 reps Gradual increase in weights; return-to-run progression Pain expected; icing post-exercise Yes Leg extension/curl (concentric, progressive 4.5–32 kg, 5×/week) None reported
(Cunha et al., 2012) Decline squat (25°), single-leg eccentric Squat bar + plates (5 kg increments) 3×/week 3×15 reps PG: max tolerated pain; WP: pain-free PG: “max pain possible”; WP: no pain Yes WP: same protocol without pain allowed None reported
(Frohm et al., 2007) Bromsman device (eccentric overload) Up to 320 kg barbell (machine) 2×/week (supervised) ~70 min/ session Load set by device, real-time feedback VAS (stop if >5) Yes Group II: One-legged decline squat (25° board, 3×15 reps, backpack) None
(Jonsson and Alfredson, 2005) 25° decline squats, 3×15 reps, twice daily Backpack (gradual increase) 2×/day 90 reps/day Load increased if pain-free Pain allowed, increase load when pain eased Yes CT: Concentric training 4/9 tendons in CT group dropped out due to pain
(Kongsgaard et al., 2009) Decline squats, 3×15 reps, 2×/day Backpack (gradual) 2×/day 90 reps/day Increase with pain decrease VAS ≤ 3–5 Yes CORT: Steroid injections + eccentric None reported
(Knež and Hudetz, 2023) Decline squats (17° board) Backpack (gradual increase) 2×/day 90 reps/day Increase if pain tolerated VAS ≤ 5 Yes 25° decline board No adverse events
(Lee et al., 2020) Decline squats (25° board), 3×15 reps Bodyweight → backpack (+5 kg) 2×/day 90 reps/day Progress if VAS 4–5; reduce if >6–7 VAS before/ after Yes ESWT + eccentric None reported
(Niering and Muehlbauer, 2023) Eccentric squats (flat and decline board) + stretching 80% concentric– eccentric 1RM 2–3×/week 40–60 reps/week Adjust load to fatigue VAS ≤ 5 Yes ALT therapy (balance, isometrics) None reported
(Ruffino et al., 2021) Heavy slow resistance: squats, leg press, hack squat 15–6 RM progression 3×/week 4 sets/exercise Gradual load increase Pain <4/10 post-exercise Yes Flywheel training Muscle soreness only
(Sánchez-Gómez et al., 2022) Decline squats + HMB supplementation HMB 3 g/day 2×/day 30 reps/day Progression if VAS <4 VAS <4 for progression Yes Placebo supplementation None reported
(Gómez et al., 2023) Decline squats (daily) Weight vest (5 kg) if VAS <3 6×/week 30 reps/day Increase with vest if pain ≤3 VAS ≤3 No N/A Muscle soreness only
(van Ark et al., 2016) Isometric vs isotonic leg extension 80% MVC (iso), 80% 8RM (isoT) 4×/week 5×45s (iso); 4×8 reps (isoT) Increase load 2.5% weekly NRS Yes Isometric vs isotonic None reported
(Visnes et al., 2005) Decline squats (25° board), 3×15 reps, 2×/day Bodyweight → backpack (+5 kg) 2×/day 90 reps/day Load increase if pain ≤3–4; reduce if ≥6–7 Target pain ≈5/10 tolerated Yes Control: training only None reported
(Young et al., 2005) Decline vs step squats Bodyweight → backpack (+5 kg) 2×/day 90 reps/day Decline: add load if pain eased; Step: progress speed then load Decline: moderate pain allowed; Step: minimal pain only Yes Step group None reported
Achilles Tendon
(Alfredson et al., 1998) Heel drops, straight knee (gastroc) & bent knee (soleus); eccentric only Bodyweight → backpack weights → weight machine if needed 2×/day, 7d/wk 3×15 reps for each exercise (2 variations) Progressive overload when pain subsided Pain VAS during running Yes Surgical treatment + postop rehab (12m follow-up) Muscle soreness only
(Demir Benli et al., 2022) Alfredson protocol: 3×15 reps, 2×/day, 12w Bodyweight → backpack weights 2×/day 3×15 reps Progress load if tolerated, pain <5/10 VAS Yes Group 2: ESWT (4 weekly sessions) None reported
(Beyer et al., 2015) Eccentric heel drops (straight and bent knee) Bodyweight → backpack (1 kg every 2w) 2×/day 3×15 reps Gradual increase as pain diminished VAS (during activity) Yes Group 2: HSR (3×/week, heavy resistance) One tendon rupture (ECC group)
(Habets et al., 2021) Alfredson protocol (heel drops, straight + bent knee) Bodyweight → backpack (+5 kg) 2×/day 180 reps/day Load increased when pain-free Pain allowed unless disabling Yes SG: Silbernagel program (concentric–eccentric progression + plyometrics) One dropout (SG group)
(Knobloch et al., 2007) Eccentric heel drops + AirHeel wrap Backpack (5–10 kg) 2×/day 90 reps/day Load increase if tolerated VAS ≤ 5 Yes Eccentric only (no AirHeel) None reported
(Knobloch et al., 2008) Same as above Backpack (5–10 kg) 2×/day 90 reps/day Load increase if tolerated VAS ≤ 5 Yes Eccentric only (no AirHeel) None reported
(Langberg et al., 2007) Heel drops (straight/ bent knee) Backpack (+20% BW) 2×/day 90 reps/day Increase if tolerated VAS ≤ 3–5 Yes Healthy tendon comparison None reported
(Malliaras et al., 2013) Standard eccentric (80% concentric–eccentric 1RM) vs high-load eccentric (80% eccentric 1RM) 80% 1RM 3×/week 45–60 reps/week Load adjusted to fatigue Pain monitored; stop if intolerable Yes Control: no exercise None reported
(Radovanović et al., 2022) Alfredson protocol vs high-load isometric plantarflexion Alfredson: progressive load (5 kg/wk) 2×/day 45 reps/day (Alfredson); 4×4 reps (High-load) Load progression if NRS <6, exertion <3 NRS Yes Passive therapy (no loading) None reported
(Rompe et al., 2007) Heel drops, 3×15 reps, twice daily Bodyweight → backpack (5 kg) 2×/day 45 reps/day Load increased when pain subsided Pain should remain mild/moderate Yes SWT (radial shock-wave therapy) None reported
(Rompe et al., 2009) Heel drops, 3×15 reps, twice daily Bodyweight → 5 kg rucksack 2×/day 45 reps/day Load increased when pain subsided Pain mild/ moderate only Yes Eccentric + SWT None reported
(Stergioulas et al., 2008) Decline squats (progress to backpack load) Weight vest (4 kg) 4×/week 144 reps/week Progress load if VAS <50 mm VAS <50 mm Yes Placebo laser None reported
Hamstring tendon
(Verma et al., 2022) HPLT monotherapy Laser (50 J/cm2, 5W) 3×/week 6 min/session Fixed (dose-based) NPRS Yes Conventional: US + heat + Nordic hamstring eccentrics None reported
ADL = Activities of Daily Living; ALT = Alternative Therapy; BW = Bodyweight; CMJ = Countermovement Jump; CON = Control group; CONC = Concentric; CT = Concentric Training; ECC = Eccentric; EMG = Electromyography; ESWT = Extracorporeal Shock Wave Therapy; FAOS = Foot and Ankle Outcome Score; HMB = β-Hydroxy β-Methylbutyrate; HPLT = High-Power Laser Therapy; HSR = Heavy Slow Resistance; IFC = Interferential Current Therapy; IPT = Isokinetic Peak Torque; KOOS = Knee Injury and Osteoarthritis Outcome Score; MVC = Maximal Voluntary Contraction; NRS = Numeric Rating Scale; NPRS = Numeric Pain Rating Scale; PT = Patellar Tendinopathy; PTLE = Progressive Tendon-Loading Exercise; RM = Repetition Maximum; SG = Silbernagel Program; SLDS = Single-Leg Decline Squat; SWT = Shock Wave Therapy; US = Ultrasound; USGET = Ultrasound-Guided Galvanic Electrolysis Technique; VAS = Visual Analog Scale; VISA-A = Victorian Institute of Sport Assessment–Achilles; VISA-P = Victorian Institute of Sport Assessment–Patella; WP = Without Pain group.